493 research outputs found
Initial results from the Caltech/DRSI balloon-borne isotope experiment
The Caltech/DSRI balloonborne High Energy Isotope Spectrometer Telescope (HEIST) was flown successfully from Palestine, Texas on 14 May, 1984. The experiment was designed to measure cosmic ray isotopic abundances from neon through iron, with incident particle energies from approx. 1.5 to 2.2 GeV/nucleon depending on the element. During approximately 38 hours at float altitude, 100,000 events were recorded with Z or = 6 and incident energies approx. 1.5 GeV/nucleon. We present results from the ongoing data analysis associated with both the preflight Bevalac calibration and the flight data
A Cerenkov - ΔE/ΔX Experiment for Measuring Cosmic-Ray Isotopes from Neon Through Iron
A ballon-borne cosmic-ray experiment has been constructed to measure cosmic-ray isotope masses, It employs a pair of Cerenkov counters and a NaI scintillator stack to determine changes in ΔE in energy and Δγ in Lorentz factor for a traversing or stopping particle. Mass M = ΔE/Δγ. Mass resolution better than 0.3 a.m.u. is expected for incident elements from neon through iron, with incident Lorentz gammas ranging from 2.4 to 3.1, depending on the element. Using data obtained at the Berkeley Bevalac, the mass resolution ∂M ≈ 2 a.m.u., measured for ^(55)Mn ions with incident γ = 2.5
Initial Results from the Caltech/DSRI Balloon-Borne Isotope Experiment
The Caltech/DSRI balloonborne High Energy Isotope Spectrometer Telescope (HEIST) was flown successfully from Palestine, Texas on 14 May, 1984. The experiment was designed to measure cosmic ray isotopic abundances from neon through iron, with incident particle energies from ~1.5 to 2.2 GeV/nucleon depending on the element. During ~38 hours at float altitude, > 10^5 events were recorded with Z ≥ 6 and incident energies ≳ 1.5 GeV/nucleon. We present results from the ongoing data analysis associated with both the preflight Bevalac calibration and the flight data
A Measurement of the Isotopic Composition of Cosmic Ray Iron
We present a new measurement of the isotopic composition of cosmic ray iron in the energy
interval ~1550-2200 MeV /nucleon. The data were collected during the May 1984 flight of a balloon-borne spectrometer and show an average mass resolution of ~0.7 amu. The instrument employed the Cerenkov-Energy technique for mass determination. The observed ^(54)Fe/^(56)Fe ratio, 0.14 +0.18/-0.11 at the top of the atmosphere, is consistent with a solar system composition at the cosmic ray source. We also place an upper limit on the ^(58)Fe/^(56)Fe ratio at the top of the atmosphere of ≤.07. Both are consistent with previous
measurements at lower energies
Nova light curves from the Solar Mass Ejection Imager (SMEI) - II. The extended catalogue
We present the results from observing nine Galactic novae in eruption with the Solar Mass Ejection Imager (SMEI) between 2004 and 2009. While many of these novae reached peak magnitudes that were either at or approaching the detection limits of SMEI, we were still able to produce light curves that in many cases contained more data at and around the initial rise, peak, and decline than those found in other variable star catalogs. For each nova, we obtained a peak time, maximum magnitude, and for several an estimate of the decline time (t2). Interestingly, although of lower quality than those found in Hounsell et al. (2010a), two of the light curves may indicate the presence of a pre-maximum halt. In addition the high cadence of the SMEI instrument has allowed the detection of low amplitude variations in at least one of the nova light curves
Infrared skin damage thresholds from 1940-nm continuous-wave laser exposures
A series of experiments are conducted in vivo using Yucatan mini-pigs (Sus scrofa domestica) to determine thermal damage thresholds to the skin from 1940-nm continuous-wave thulium fiber laser irradiation. Experiments employ exposure durations from 10 ms to 10 s and beam diameters of approximately 4.8 to 18 mm. Thermal imagery data provide a time-dependent surface temperature response from the laser. A damage endpoint of minimally visible effect is employed to determine threshold for damage at 1 and 24 h postexposure. Predicted thermal response and damage thresholds are compared with a numerical model of optical-thermal interaction. Results are compared with current exposure limits for laser safety. It is concluded that exposure limits should be based on data representative of large-beam exposures, where effects of radial diffusion are minimized for longer-duration damage threshold
Biodiversity into your hands - A call for a virtual global natural history 'metacollection'
10.1186/1742-9994-10-55Frontiers in Zoology101
On the autonomous detection of coronal mass ejections in heliospheric imager data
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95523/1/jgra21843.pd
Moon Shadow by Cosmic Rays under the Influence of Geomagnetic Field and Search for Antiprotons at Multi-TeV Energies
We have observed the shadowing of galactic cosmic ray flux in the direction
of the moon, the so-called moon shadow, using the Tibet-III air shower array
operating at Yangbajing (4300 m a.s.l.) in Tibet since 1999. Almost all cosmic
rays are positively charged; for that reason, they are bent by the geomagnetic
field, thereby shifting the moon shadow westward. The cosmic rays will also
produce an additional shadow in the eastward direction of the moon if cosmic
rays contain negatively charged particles, such as antiprotons, with some
fraction. We selected 1.5 x10^{10} air shower events with energy beyond about 3
TeV from the dataset observed by the Tibet-III air shower array and detected
the moon shadow at level. The center of the moon was detected
in the direction away from the apparent center of the moon by 0.23 to
the west. Based on these data and a full Monte Carlo simulation, we searched
for the existence of the shadow produced by antiprotons at the multi-TeV energy
region. No evidence of the existence of antiprotons was found in this energy
region. We obtained the 90% confidence level upper limit of the flux ratio of
antiprotons to protons as 7% at multi-TeV energies.Comment: 13pages,4figures; Accepted for publication in Astroparticle Physic
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